1. Field of the Invention
This invention relates to photographic apparatus of the self-developing type.
2. Description of the Prior Art
Photographic apparatus of the self-developing type are well known and generally comprise, e.g., a camera having a pair of pressure-applying members through which an exposed film unit is advanced while a processing composition is spread across a photosensitive layer of the film unit to initiate formation of a visible image in the film unit. The treated film unit is then advanced to a light tight chamber wherein it remains for a period of time sufficient for a visible image to be substantially formed therein. Examples of cameras of the foregoing type may be found in U.S. Pat. Nos. 2,873,658; 3,396,647; and 3,537,370. Each of these patents shows a camera having a chamber for receiving at least a portion of a film unit as it is advanced from between a pair of rollers. The chambers in the first two mentioned patents function to prevent further exposure of a treated film unit to the ambient light while the chamber in U.S. Pat. No. 3,537,370 cooperates with a curtain in the form of a coil of opaque sheet material to prevent further exposure of an untreated film unit. In the latter patent, the leading edge of a film unit is adapted to engage a member on an end of the sheet and uncoil the curtain as they move together past a viewfinder, thereby preventing further exposure of the film unit to light passing through the viewfinder. However, while the foregoing arrangements performed their function well, the chambers added to the overall dimensions of the cameras thereby placing them at an economic disadvantage relative to similar cameras of a more compact design.
Lately, there has been disclosed a family of film units of the self-developing type which can be advanced into the ambient light substantially immediately after the processing composition has been spread across at least a predetermined length of the film unit. One example of this type of film unit is described in U.S. Pat. No. 3,415,644, granted to Edwin H. Land, on Dec. 10, 1968. Film units of this type enhance the compactness of cameras with which they are adapted to be used in that the cameras may be designed to advance a section of the film unit which has been treated with a processing composition from the camera while a section of that film unit yet untreated with the processing composition still remains within the camera.
It has most recently been suggested that compact cameras adapted for use with film units of the above-described type also be utilized with film units of the transparency type. Transparencies generally comprise a positive image superposed on a transparent or translucent support and may be either directly viewed by transmitting light through the transparency to the eye of an observer or indirectly viewed by transmitting light through the transparency for projection on a screen. More specifically, the transparency includes two spaced apart outside layers or elements which are substantially light transparent and may comprise a polyester, such as a polymeric film derived from ethylene glycol terephthalic acid or a cellulose derivative such as cellulose triacetate. Intermediate the outside transparent layers, there is provided a photosensitive silver halide stratum together with an optical screen element or reseau which possesses filter or screen elements for selectively transmitting predetermined portions of the actinic radiation incident to the screen. The transparency would additionally employ an image receiving component intermediate the photosensitive silver halide stratum and the optical screen element as well as a rupturable pod of processing fluid adjacent one edge of the transparency. During exposure operations, image-carrying light rays from the camera's lens pass through one of the transparent outside layers as well as the screen unit and image-receiving component to expose the silver halide stratum. The transparency is subsequently advanced between a pair of spread rollers and towards the film exit means of the camera, whereupon the spread rollers progressively distribute a mass of the processing composition intermediate the silver halide stratum and its adjacent transparent layer. Once the mass of processing composition has been spread, sufficient imbibing time must be allowed in a light tight environment in order to complete the silver diffusion transfer process by which a positive image is formed on the image receiving component. However, as previously discussed, providing a light tight chamber into which the transparency may be advanced during the silver diffusion transfer process would detract from the preferred compact camera design.
Additional problems arise with respect to providing a light tight environment for a transparency in comparison with a photographic print on an opaque base. The opaque base of a photographic print operates to shield one side of the photosensitive layer from premature exposure, and thus it is sufficient to shield only the other side of the photosensitive layer in order to provide a totally light tight environment for processing. However, transparencies do not embody an opaque base portion and thus must be shielded from both sides in order to provide the light tight environment required to complete the diffusion transfer process subsequent to the processing fluid being spread by the spread rollers.
Therefore, it is a primary object of this invention to provide a photographic apparatus which may be utilized to provide transparencies of the self-developed type.
It is a further object of this invention to provide a photographic apparatus adapted for use with transparencies of the self-developing type whereby the transparencies may be advanced outside the photographic apparatus and still maintained in a light tight environment for sufficient time to complete the diffusion transfer process.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the mechanism and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the followed detailed disclosure.